1. Field of the Invention
The present invention relates to an industrial robot such as an articulated robot for performing an operation by a tool mounted to the tip of an arm.
2. Description of the Related Art
Generally, so-called articulated robots and other robots are widely used as industrial robots such as welding robots. An articulated robot includes a tool mounting portion, to which a tool is to be mounted, at a tip portion and the tool is detachable if necessary. Some of industrial robots of recent years are so constructed that one industrial robot successively performs various operations by itself by automatically exchanging a plurality of types of tools according to a program.
Such an industrial robot includes a locking mechanism for locking a tool and a tool mounting portion to reliably perform operations by preventing detachment of the tool from the tool mounting portion. The locking mechanism is driven, for example, by air supplied to the tool mounting portion to lock and unlock the tool and the tool mounting portion.
Conventionally, it has been a general practice to arrange a pipe for supplying air to a tool mounting portion outside an arm in an industrial robot, for example, as disclosed in JP-A-H11-239992 (hereinafter, referred to as patent literature 1). For example, for an industrial robot in which air is supplied to a working tool, there has been proposed a piping structure in which a pipe passed inside is taken out near a wrist portion and air is supplied to the wrist portion.
However, if the pipe is located at an outer side of the arm near the wrist portion in the industrial robot as disclosed in patent literature 1, the pipe may interfere with an external structure and may be broken in some cases. Further, the pipe may be entangled around an external structure and may become unable to supply air.
The industrial robot may be so constructed as to arrange the pipe in the arm, but the pipe may be twisted or buckled near a rotating shaft of the arm and a large space needs to be taken for a pipe path. However, if a large space is taken for the pipe path, an area around the rotating shaft of the arm becomes larger, thereby limiting application in a narrow place or the like.